javascript - 如何在 QML 中执行 "is_a"、 "typeof"或 instanceof ？

Question

我想遍历 QML 组件列表并选择一种类型:

for (var i = 0; i < controls.children.length; ++i) {
     if ( typeof (controls.children[i].height) == "QDeclarativeRectangle")
     {
        // do stuff
     }
}

如何做到这一点？

Answer 1

从 Qt 5.10 开始，您终于可以使用 instanceOf 来检查变量是否属于某种 QML 类型，参见 "QML Support for Enum and InstanceOf Type Checks" .

import VPlayApps 1.0
import QtQuick 2.0

App {
  // two QML items, used for type checking
  Item { id: testItem }
  Rectangle { id: testRect }

  // function to check wheter an item is a Rectangle
  function isRectangle(item) {
    return item instanceof Rectangle
  }

  // type check example
  Component.onCompleted: {
    console.log("testItem is Rectangle? " + isRectangle(testItem))
    console.log("testRect is Rectangle? " + isRectangle(testRect))
  }
}